1. Field of the Invention
The invention relates to a process for stripping an insulated wire or cable (electric or optical) having a cross-section which may be non-circular, and a stripping device for carrying out the process.
2. Most closely related prior art
U.S. Pat. No. 4,543,717 of Tektronix Inc. describes a stripping device in which an axially acting--with respect to a cable to be stripped--and a radially acting stripping blade are each held on a swivel arm and can be swivelled independently of one another and in succession towards the cable inserted into the device. First the radially acting blade is swivelled into the insulation and this blade is then rotated around the cable, making a circumferential cut through the insulation. Thereafter, the radial blade is swivelled away from the cable and the axial blade is swivelled into the insulation. As a result of pulling out the cable--by hand--the insulation is then provided with a longitudinal cut. The axial blade is then swivelled back to its starting position. The circumferential cut and longitudinal cut permit removal of the piece of insulation. A device according to the teaching of the U.S. Patent is on the market under the name Maranatha Cable Stripper. The following problems arise in the case of these known devices:
With the same length setting, the arrangement of the blades on the swivel arm results in axially different contact points of the blades on the insulation as a function of the cable diameter, so that the accuracy of adjustment is low. To achieve a certain exact cut for a certain cable, it is therefore necessary as a rule to make several trial cuts in order to achieve the correct setting by trial and error. This is time-consuming and in particular disadvantageous if the stripping device is to be automated, since cumulative errors may occur under certain circumstances.
Swivelling of the blades also results in a different inclined position of the radial blade with respect to a radial plane through the cable once again as a function of the cable thickness. This leads under certain circumstances to cut surfaces which in fact also do not lie in a radial plane, which, when the cable is further processed with highly precise requirements, may be problematic or may lead to insulation defects.
In the case of thick insulation layers, there may therefore also be jamming at the lateral surfaces of the radial blade since the latter is moved along a cylinder lateral surface while cutting into the insulation and the resulting curved cut insulation surface rubs against the essentially straight lateral surface of the radial blade.
A further problem may be the adjustment of the radial blade with respect to the axial blade since, owing to the fact that the cut surfaces of these blades are perpendicular to one another, different initial points of attack on the outer sheath of the cable may also result in the case of different cable thicknesses. However, it must be ensured that the respective circumferential cuts intersect the respective axial cuts. This may give rise to additional adjustment work.
Another more recent stripping device for noncircular cable is described in U.S. Pat. No. 4,557,163 of Boeing. However, this device does not permit a clean circumferential cut. In addition, the device itself must be moved along the cable. It is thus of no help for solving the above problems.
Another stripping device with an earlier priority date is described in U.S. Pat. No. 4,546,675 of Tokyo Shibaura, the teaching of which is evidently the prior art for the most closely related U.S. Pat. No. 4,543,717 cited. This device was provided with radial and axial blades which are separated spatially and with regard to movement from one another in relation to the longitudinal axis of one cable and which furthermore were in the form of rotating cutter disks. This device thus permitted stripping of exclusively continuous cable since it was first necessary to make an axial cut for complete axial and radial incision, which is scarcely possible in the stripping of cable ends since in such a case it was necessary to push against the axial blade when inserting the cable into the device, which is not possible especially in the case of relatively thin cables. A combination of the positions of the two independent blades is not possible in this known design. Although this known device thus avoids the disadvantages of the cable diameter dependence and the inclined or curved cut surfaces, it cannot be used at all in a large number of processes for stripping cable end sections. Moreover, this device has large dimensions and requires separate, additional drives for the rotatable blades.